Wire-type slide resistor for a self-balancing instrument having contact position regulating means

ABSTRACT

A slide resistor for a self-balancing instrument including two retainers provided within a frame of the self-balancing instrument, each retainer being provided with two notches. Two wire resistors are stretched between the two retainers, one end of each wire resistor being fastened to one of the two retainers by a conductive terminal engaged to a respective notch, and the other end being fastened to the other retainer through a conductive spring by a conductive terminal engaged to the notch of the other retainer. A slide contact is secured to a movable body and is adapted to slide on the wire resistors, and a roller is provided on the movable body adjacent the slide contact, the roller being provided with two V-shaped grooves to guide the two wire resistors, respectively.

United States Patent 1 1 Kurimoto et al.

[451 Nov. 20, 1973 [75] Inventors: Kozo Kurimoto; Hiroshi Umetsu;

Takeo Shoji, all of Katsuta; Yukio Yoshinari, Naka, all of Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: Nov. 11, 1971 [21] Appl. N0.: 197,875

[30] Foreign Application Priority Data [56] References Cited UNITED STATES PATENTS 9/1944 Side 338/126 X 2,055,766 9/1936 Hunt 338/197 X 2,234,155 3/1941 Bliss 338/150 FOREIGN PATENTS OR APPLICATIONS 364,647 11/1938 Italy 338/79 Primary Examiner-Robert K. Schaefer Assistant Examiner-Gerald P. Tolin Att0rney-Craig, Antonelli & Hill [57 ABSTRACT A slide resistor for a self-balancing instrument including two retainers provided within a frame of the selfbalancing instrument, each retainer being provided with two notches. Two wire resistors are stretched between the two retainers, one end of each wire resistor being fastened to one of the two retainers by a conductive terminal engaged to a respective notch, and the other end being fastened to the other retainer through a conductive spring by a conductive terminal engaged to the notch of the other retainer. A slide contact is secured to a movable body and is adapted to slide on the wire resistors, and a roller is provided on the movable body adjacent the slide contact, the roller being provided with two V-shaped grooves to guide the two wire resistors, respectively.

12 Claims, 5 Drawing Figures PATENTED KEY 20 I975 sum 2 BF 2 FIG.'5'

BACKGROUND OF THE INVENTION This invention relates to slide. resistor for selfbalancing instruments. The invention is described herein in connection with self-balancing recorders.

As is well known in the art, in the conventional selfbalancing recorder, a recording pen is moved in proportion to the signal input to record the input value on a recording sheet. It is provided with slide resistor means for converting the position of the recording pen into a corresponding electric signal.

The slide resistor means of this kind is usually provided in the form of a coil resistor type device consisting of a coil resistor wound on a thick core wire. In the coil resistor type slide resistor means, however, a slide tap slides along a surface of the coil turns of the resistor. Therefore, for the recording of a continuously changing input the resolutionpower of the recorder is unsatisfactory since the recording pen is moved from one coil turn to the next providing a change in resistance which is stepwise. Also, since the coil resistor itself is comparatively large in size, the recorder also tends to have a large size, which conflicts with the demand for size reduction in such devices. Further, with recent increase in the response speed of the recording pen of the recorder, the slide tap is liable to stride several turns of the coil resistor. Furthermore, as the slide tap wears, contact failure will result due to insufficient contact pressure.

In order to eliminate the above drawback, it has presently been proposed to use two wire resistors (one wire resistor being usedas a lead wire) stretched parallel to each other and a U-shaped plate spring provided with contacts on the inner side of the opposite legs, said plate spring beingsecured to a recording pen holder and clamping the two wire resistors so that. the contacts are in frictional engagement with the wire resistors, saidwire resistors being stretched between two cylindrical guides secured to the recording pen holder on opposite sides of the plate spring and having a diameter slightly greater thanv the distance between the contacts. .With this construction, the contact pressure between the contact and the wire resistor can always be maintained constant.

With this construction, however, the contact touches the wire resistor at various positions with the movement of the recording pen holder, resulting in contact failure. This is because the contact and the wire resistor are both made of metal so that grooves are formed in the contact due to the sliding movement of the contact along the wire resistor Also, the cylindrical guides are usually made of an insulating material, such as acetalhomopolymer and glass, which produces a powder discharge with wear, and as a result of contact with the wire resistors, the powder attaches to the wire resistors to cause contact failure, resulting in fluctuations of therecording output, that is, fluctuations in the indication of the indicating means. Thus, a smooth recording cannot be ensured.

soon broken, so that the service life of the wire resistors, that is, the number 'of reciprocations of the recording pen holder, is very shorLFurthermore, since the contacts are secured to the plate spring wiper, tedious adjustment of the plate spring is necessary during manufacture.

SUMMARY OF THE INVENTION The invention has an object of providing a slide resistor device for self-balancing instruments, which is simple in construction and which makes it possible to maintain excellent contact between the contact and the wire resistors.

Another object of the invention is to provide a slide resistor for self-balancing instruments in which the replacement of the wire resistor may be readily accomplished.

A further object of the invention is to provide a slide resistor for self-balancing instruments which can be inexpensively and simply manufactured.

A still further object of the invention is to provide a slide resistor for self-balancing instruments in which the service life of the wire resistor is very long.

According to the invention, satisfactory sliding contact between at least one wire resistor and a slide contact securedto a movable part of the self-balancing recorder can always be maintained by a simple regulating means regulating the positions of contact between the wire resistor and the slide contact.

Also, according to the invention, the regulating means consists of a roller provided with guide grooves to guide the wire resistor and lightly touching them while it rotates, so that no discharge of powder resulting from wear is produced, thereby to ensure excellent contact between the wire resistor and the slide contact, as well as extending the service life of the wire resistors.

Further, according to the invention, it is possible to replace the wire resistor without removing the retainers, adjust the tension of the wire resistors and facilitate the assembling of the instrument and replacement of the wire resistor.

BRIEFDESCRIPTION OF THE DRAWINGS FIG. 4 is a detail view of an improved construction of the retainer used in the above embodiments; and

FIG. 5 is a detail view ofa further improved construction of the retainer.

DETAILEDDESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, wire resistors la and lb are made of thin manganin wires, for instance, which are Further, with the cylindrical guides made of acetalhomopolymer, sufficient contact pressure between the contact and the wire resistor cannot be obtained due to the unavoidable wear of the cylindrical guides. In the case where glass guides are used, the wire resistors are stretched horizontally and parallel to each other between two non-conductive retainers 3 and 5. One end of each wire resistor is fixed at a conductive terminal 7a or 7b attached on a vertical wall of the retainer 3. The other vertical wall of the retainer 3 has two slits 9a and 9b through which the wire resistors la and 1b are stretched. In the retainer 5, the other end of each wire resistor is connected to a conductive relay terminal 1 1a or llb through a slit 15a or 15b. The terminals 11a and 11b do not contact the retainer 5, but are supported by the tension of the conductive springs 13a and 13b to which they are respectively connected. The springs 13a and 13b are further connected to conductiveterminals 17a and 17b, respectively, which are fastened to the retainer 5, so that the springs 13a and 13b apply a desirable tension to the wire resistors 1a and lb.

A rider shaft 19 is provided along which a recording pen holder 21 is moved. The recording pen holder 21 is molded from a plastic material and has an L-shaped attachment member 23 secured by a bolt to the holder. To the member 23 is welded a contact 25 made of a Au-Pd material, for instance, which contact is in frictional engagement with the wire resistors 1a and lb. The holder 21 further has a guide roller 27 formed with two guide grooves for guiding the wire resistors 1a and lb. The contact 25 and the roller 27 are disposed relative to each other so as to provide a predetermined contact pressure between the contact 25 and the wire resistors la and lb.

In the case of FIG. 1, the roller 27 is placed at a higher position than the surface of the contact 25; therefore, the wire resistors 1a and lb are stretched through the upper side of the roller 27 and the lower side of the contact 25. These conditions are obvious from FIG. 2, which shows a cross-sectional view of the holder 21. As is apparent from this figure, the grooves 33a and 33b formed on the roller 27 are V-shaped and the position of the roller 27 is higher than the surface of the contact 25. As a modification, the relationship of the relative positions of the two may be inverted, in which case the surface of the contact 25 must be turned up and the wire resistors la and lb stretched through the lower side of the roller 27 and the upper side of the contact 25.

In the above-mentioned structure, a direct current electric source 29 is connected between the terminals 7a and 17a, so that an output according to the position of the holder 21 appears across output terminals 31.

The operation of the device described above is as follows. As the holder 21 moves along the rider shaft 19 in response to the changing input, the contact 25 is moved to positions proportional to the value of the input while being maintained in contact with the wire resistors 1a and 1b. The roller 27 moving with the holder 21 is rotated by the frictional resistance between it and the wire resistors 1a and lb so that the wire resistors la and lb may touch the contact 25 at its predetermined positions.

Since the points of contact between the wire resistors 1a and 1b and the contact 25 are maintained at constant spacing by the roller 27, which is not in sliding contact with the wire resistors, but only lightly touches the wire resistors while it rotates, no powder created by wear is produced, so that there is no possibility of causing contact failure. Thus, the excellent contact between the wire resistors 1a and lb and the contact 25 may be maintained.

Experiments reveal that according to the invention no contact failure results even after the recording pen holder has been reciprocated a million times, while with the usual slide resistor means using a single wire resistor, contact failure resulted after about 200,000 reciprocations of the recording pen holder.

Also, since the roller 27 is not in sliding contact with the wire resistors, but only lightly touches them while it rotates, the service life of the wire resistors 1a and lb may be greatly extended. Further. since the wire resistors la and lb are guided in respective V-shaped grooves 33a and 33b formed in the roller 27, sufficient contact pressure between the wire resistors 10 and lb and the contact 25 may be obtained. Furthermore, since the contact 25 is secured to the steel attachment member 23, no wipe adjustment is necessary, thus facilitating the manufacture of the arrangement.

FIG. 3 shows another embodiment, in which two guide rollers 271 and 272 are provided on respective sides of the contact 25 rotatably mounted on the holder 21. Other parts of the arrangement have the same structure as shown in FIG. 1. The wire resistors 1a and lb are stretched along a V-shaped path through the upper side of the roller 271, the lower surface of the contact 25 and the upper side of the roller 272. In this way, a predetermined contact pressure may always be obtained even if the wire resistors 1a and lb become slightly loose.

In the preceding embodiments illustrated in FIGS. 1 and 3, the wire resistors 1a and 1b are stretched between the retainers 3 and 5 through the terminals provided at their opposite ends. With this construction, the assembling of the slide resistor arrangement including the wire resistors la and lb into the self-balancing instrument frame is very troublesome, since they must be installed together with the retainers 3 and 5. Also, when replacing the wire resistors la and lb the retainers 3 and 5, which are secured to the frame body,

shouldalso be replaced, so that the replacement is very troublesome and is not economical. Further, the wire resistors 10 and 1b should be cut to a predetermined length, but it is desirableto be able to adjust the wire length-to provide a predetermined contact pressure, since the tension of the wire resistors la and lb varies depending upon the length.

FIG. 4 shows a further improved retainer 5, which is intended to solve the above problems. The retainer 3 also has the same construction as retainer 5. In this embodiment, the retainer 5 is formed with notches 37a and 37b. Strip-like terminals and 17b provided with stepped portions 172 and 173 are received in the re spective notches 37a and 37b and are retained therein by the shoulders of the stepped portions 172 or 173. With this construction, the wire resistors 1a and 1b may be removably attached to the retainers 3 and 5, so that the assembling of the instrument and the replacement of the wire resistors 10 and 1b may be readily accomplished. Also, the retainers 3 and 5 need not be replaced when replacing the wire resistors la and lb, which is very economical. Further, by changing the shoulders in each of the stepped portions 172 and 173 of the terminals 17a and 17b which engage the notches 37a and 37b, the tension of the wire resistors 1a and 1b may be adjusted. Furthermore, as shown in FIG. 5, in order to insure holding the terminals 17a and 17b in the notches 37a and 37b, a groove 51 may be horizontally provided in an outer side of the vertical wall of the retainer 5 so as to engage the notches 172 and 173 therein.

Having thus described the present invention, it is obvious that various modifications within the knowledge of workers in the art may be utilized without departing therefrom. 1

It is to be understood also that although the invention has been described with specific reference to some particular embodiments thereof, it is notto be so limited,

which are within the full intended scope of this invention as defined by the appended claims.

What is claimed is:

1. A slide resistor arrangement for self-balancing instrument comprising at least one wire resistor stretched under a predetermined tension, a rigid non-resilient slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, and contact position regulating means secured to said movable body for regulating said wire resistor maintaining the contact position between said slide contact and said wire resistor at predetermined positions of said slide contact by controlling the tension in said wire resistor thereby maintaining the wire resistor in contact with said slide contact.

2. A slide resistor arrangement according to claim 1 wherein said contact position regulating means comprises at least one roller provided on said movable body adjacent said slide contact, said roller being provided with a groove guiding said wire resistor.

3. A slide resistor arrangement according to claim 2 .wherein said contact position regulating means comprises two rollers provided on respective sides of said slide contact so that said wire resistor-is stretched in a terminal engaging in the notch of that retainer, a slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, and contact position regulating means secured to said movable body for regulating said wire resistor to maintain the contact position between said slide contact and said wire resistor at predermined positions of said slide contact.

5. A slide resistor arrangement according to claim 4 wherein each terminal at the ends of said wire resistor 6 has a plurality of stepped portions engaging in respective notches of said retainers.

6. A slide resistor arrangement according to claim 5 wherein each retainer has a groove engaging said stepped portions of the terminal. i

7. A slide resistor arrangement according to claim 4 wherein said contact position regulating means comprises at least one roller provided on said movable body adjacent said slide contact, said roller being provided with a groove guiding said wire resistor.

8. A slide resistor arrangement according to claim 4 wherein said contact position regulating means comprises two rollers, secured to said movable body on respective sides of said slide contact, so that said wire resistor is stretched in a V-shaped form in the area of said slide contact.

9. a slide resistor arrangemnt according to claim 4 including at least two wire resistors in contact with said slide contact stretched between said two retainers, each wire resistor being fastened to said retainers by a conductive terminal and a conductive spring connected to the respective ends thereof.

10. In a slide resistor arrangement for a selfbalancing instrument having at least one substantially straight uni-directional wire resistor stretched under a predetermined tension, and a rigid non-resilient slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, the improvement comprising: wire resistor contact regulating means secured to said movable body for positioning the wire resistor and maintaining said slide contact on said movable body in engagement with said wire resistor at predetermined positions along said wire resistor.

11. A slide resistor arrangement according to claim 10, whereinsaid wire resistor contact regulating means comprises at least one roller provided on said movable body adjacent to said slide contact, said roller being provided with a groove for guiding said wire resistor.

12. A slide resistor arrangement according to claim 11, wherein said wire resistor contact regulating means comprises two rollers provided on respective sides of said slide contact so that said wire resistor is stretched in a V-shaped form in the area of said slidecontact.

l l l 

1. A slide resistor arrangement for self-balancing instrument comprising at least one wire resistor stretched under a predetermined tension, a rigid non-resilient slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, and contact position Regulating means secured to said movable body for regulating said wire resistor maintaining the contact position between said slide contact and said wire resistor at predetermined positions of said slide contact by controlling the tension in said wire resistor thereby maintaining the wire resistor in contact with said slide contact.
 2. A slide resistor arrangement according to claim 1 wherein said contact position regulating means comprises at least one roller provided on said movable body adjacent said slide contact, said roller being provided with a groove guiding said wire resistor.
 3. A slide resistor arrangement according to claim 2 wherein said contact position regulating means comprises two rollers provided on respective sides of said slide contact so that said wire resistor is stretched in a V-shaped form in the area of said slide contact.
 4. A slide resistor arrangement for a self-balancing instrument comprising two retainers provided within a frame of the self-balancing instrument, each retainer being provided with at least one notch, at least one wire resistor stretched between said two retainers, one end of the wire resistor being fastened to one of said two retainers by a conductive terminal engaging in the notch therein and the other end being fastened to the other retainer through a conductive spring by a conductive terminal engaging in the notch of that retainer, a slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, and contact position regulating means secured to said movable body for regulating said wire resistor to maintain the contact position between said slide contact and said wire resistor at predermined positions of said slide contact.
 5. A slide resistor arrangement according to claim 4 wherein each terminal at the ends of said wire resistor has a plurality of stepped portions engaging in respective notches of said retainers.
 6. A slide resistor arrangement according to claim 5 wherein each retainer has a groove engaging said stepped portions of the terminal.
 7. A slide resistor arrangement according to claim 4 wherein said contact position regulating means comprises at least one roller provided on said movable body adjacent said slide contact, said roller being provided with a groove guiding said wire resistor.
 8. A slide resistor arrangement according to claim 4 wherein said contact position regulating means comprises two rollers, secured to said movable body on respective sides of said slide contact, so that said wire resistor is stretched in a V-shaped form in the area of said slide contact.
 9. a slide resistor arrangemnt according to claim 4 including at least two wire resistors in contact with said slide contact stretched between said two retainers, each wire resistor being fastened to said retainers by a conductive terminal and a conductive spring connected to the respective ends thereof.
 10. In a slide resistor arrangement for a self-balancing instrument having at least one substantially straight uni-directional wire resistor stretched under a predetermined tension, and a rigid non-resilient slide contact secured to a movable body positioned to slide with said contact in engagement with said wire resistor, the improvement comprising: wire resistor contact regulating means secured to said movable body for positioning the wire resistor and maintaining said slide contact on said movable body in engagement with said wire resistor at predetermined positions along said wire resistor.
 11. A slide resistor arrangement according to claim 10, wherein said wire resistor contact regulating means comprises at least one roller provided on said movable body adjacent to said slide contact, said roller being provided with a groove for guiding said wire resistor.
 12. A slide resistor arrangement according to claim 11, wherein said wire resistor contact regulating means comprises two rollers provided on respective sides of said slide contact so that said wire resistor iS stretched in a V-shaped form in the area of said slide contact. 